A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines.
A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds.
The gear assembly requires lubricant flow during operation and anytime the gear assembly is moving. A lubrication system typically includes a pump driven by operation of the engine. However, when the engine is not operating, the fan and gear assembly may still rotate and require lubricant. Moreover, operation in a negative-G environment can disrupt lubricant flow. The lubrication system is therefore required to provide a minimum lubricant flow regardless of current engine operation and environmental conditions.